I think you should definately take him to a vet if he doesn't go soon. I had a cat once that died of a urinary tract blockage. I didn't even notice a problem. He was a little irritable for a day or two but I thought he was just sick of the dogs bothering him. I woke up one morning and he was very ill and couldn't lift his head. My husband at the time took him to the vet and came to my work a few hours later telling me that he had passed away. Apparently it was a condition somewhat common is male cats that have been "fixed". Don't know about dogs though. My vet did tell me that I need to watch for habit changes in the future and if I have a cat that stops peeing to not wait. Just something to think about. Better safe than sorry.